Tankless Water Heater Recirculation Pump
 

Has anyone installed a Tankless water heater recirculation pump on their Rheem water heater outside? Looking for some options to get faster hot water. Is this a DYI or do you need a professional? Any recommendation on brands and how your experience was?

You need a special pump that has enough flow to start the tankless system. Call Mike Scott or another professional.

This recent conversation might help
https://www.talkofthevillages.com/fo...=recirculating

You do realize this will cause the tankless water heater to run much more often. IMHO, if this is a big problem, have another electric tankless water heater installed in the bathroom, figure on at least $1000. I saved a lot of money, I turn on the shower to full hot, count to 30, move the handle back to the normal shower position wait 5 seconds and the shower is ready.

Another thing you can do is to turn on the hot water sink faucet, which will reduce the 30 seconds to about 15 seconds or less.

The idea is to install the pump then have it controlled with a smart switch so you can turn it on or off with Google or Alexa with your voice.

The above 2 replies are excellent, I was thinking of the older timer based solution.

I have a pump on my old fashion hot water heater. The system circulates the hot water back to my tank in the cold water line. How would this work on a tankless system? The question is where does the cold water go that you are pushing out of the hot water line?

With a regular tank hot water heater you can buy and install the circulator pump on-line or at home depot. Very easy.

If you have a tankless system, this pump may not work because the tankless needs a certain amount of flow before it will turn On. That's why unless you know what you are doing, best to get a professonal to install it then you can add the wifi switch to control it with Google or Alexa.

Check the warranty. Mine says the warranty is void if a pump is installed. There are some that come with the ability to handle a recirculating pump.

2nd Small Tank Necessary
 

A Watts recirculating pump and a tankless water heater are not compatible for the reason there is no where for the water to "recirculate".

With a traditional 40-60 gal water heater, the Watts recirculating pump pushes hot water from the tank at low pressure through the hot water line. By reason of an innovative manifold that is installed at the faucet furthest from the water heater, the hot water being moved by the Watts pump goes into the cold water line and back to the water heater. In other words, it "recirculates" in a closed loop.

This only happens when all the cold water taps at all the faucets and showers are closed. If a cold water tap or shower is open, the valves in the manifold close and the water being pushed by the Watts pump does not enter the cold water line. It's an ingenious system and provides hot water at all the faucets and showers in the house within seconds.

To use the Watts pump with a tankless water heater, you will need to install a 2nd hot water heater after the tankless heater to serve as a reservoir of hot water which can then be recirculated by the Watts pump. Small tanks of this type are 7-10 gallons in size and are readily available at Home Depot and Lowes.

With a standard hot water heater, the Watts pump is an easy DIY or it can be installed by a handyman. Adding a second, small, tank after a tankless heater is more complicated and should, probably, be left to a plumber.

Buyers of tankless water heaters are often under the impression that they will have "instant" hot water. They will, but only at the outlet of the tankless heater. Just as with a regular water heater, the hot water from a tankless heater has to flow to the faucets and showers inside the house before there is hot water at them.

Install a Watts pump. You'll never regret doing so. One final piece of advice--in some houses in The Villages, such as our Magnolia model, the hot water line "splits" and goes in two directions after it enters the house. This requires a second manifold so that there is one at the end of each line. The extra manifold costs approximately $50.

You need much more than just putting a pump o the hot water line, you need all the plumbing that goes with it. If you stick a pump on the hot water line by itself, you will blow the line apart overtime time.
Also you don’t use the cold water line as the return line. If this was the case you would never have cold water.
A hot water recirculating system is 1 big loop of the hot water line with drops for each kitchen and bath. The water from the heater flows in a circle keeping the water at a temperature you program at the pump, not at the heater. If you set the water heater at 120 and the recirculating pump is set at 122, your water will run constantly because it’s trying to heat the water to something higher than your heater. Don’t do this. I always set my pumps to a temp of 3-5 degrees colder so the pump would shut off for periods and when we needed water, it was only a couple degrees off the max setting ofthe heater and we had instant hot water at every location

I have a friend in Fenney who has an instant hot water system and he had Mike Scott install a pump with the bypass device on his system. It's been working well for a couple of years now. It's conneced via a wifi switch connected to Google so it only runs when they need hot water.

You can’t do that because a tankless does not really store any hot water. It only works when you have a tank full of hot water.

Here’s an answer
 

Put one of these under the sink of your furthest faucet (usually the master). Fairly easy install for a DIY or simple for tradesman. I have installed these on all my homes.

The one below is an extra one I have advertised on Nextdoor.

Title should say, this may be an answer

Here’s what I have. A 6 gallon water heater with a recirculating pump that uses check valves that route the water back through the cold water lines. I have this at three locations. I wouldn’t recommend the company I used but the system works great. The only downside is that there is no way to do the showers unless you tear the walls apart.

I have a rather large house up here in the Frozen north and the time it takes to push out the cold water and start the flow of hot can be ages (it seems) So naturally I asked the same question. I found that My Rheem water heater is of an age that it can not be upgraded with a pump. While that might not be in your case it does require a plumber to determine if it is possible.

Assuming you have dual sinks in the master bath just open both hot water faucets and shower. You will get hot water in 30 sec and about a gallon down the drain. Shut off the faucets and take a hot shower. More flow (demand) makes the on demand system kick in to high heat. You can hear outside it if you want to experiment with it.
Might want a small heater under the kitchen sink if that’s an issue.

That is somewhat inaccurate. Yes a tankless system does not store hot water. But water is stored in the pipes from the heater to your various faucets through out the house. When you call for hot water that water in the pipes is typically cold and that's what you get until the new hot water can push it out of the faucets. A recirculating pump removes that cold water and pushes it back into the cold water in front of the water heater. Without the cold water in it's way the hot water can reach the faucets faster.

Different System
 

You are not describing a Watts system which has been retrofitted to an existing house. The Watts system uses a low pressure pump to move water from the water heater through the hot water line to a manifold (valves) placed at the faucet or fixture furthest from the water heater. When the cold side of that faucet or fixture is turned off, the valves in the manifold direct the hot water into the cold water line which carries it back to the water heater. If the cold side of the furthest faucet or any cold side of any faucet in the system is open, the valve in the manifold closes and the hot water flow is stopped. The Watts pump is very low pressure, 2-3 lbs, and the pressure in the cold line is 30-50 lbs, which means that flowing cold water will always control the valve in the manifold.

In contrast to a Watts pump that has been fitted to an existing system, in new construction a separate return line (the 3rd line-hot, return, cold) is installed and the water being pushed by the Watts pump is returned to the water heater by the separate return line and not the cold water line.

When the Watts system is installed in an existing house and the cold water line is used as the return line, the water at the faucet on the cold side will be warm when first opened and will remain warm for the 30 or so seconds it takes for cold water to purge the hot water which has been running in the line. This is the exact opposite of waiting for hot water to reach the faucet when there is no recirculating system. I much prefer having hot water in a 2-3 seconds after opening the faucet and waiting 30 seconds for cold water than waiting 30 seconds for hot water.

Existing houses can have a separate return line installed, although it is expensive. Usually, this would be done in a house with a basement where the pipes are readily accessible. When the house is on a slab and the water lines are installed in or under the slab, it is not practical to install a 3rd line, hence, the ingenious manifold made by Watts which directs the hot water being circulated by the Watts pump into the cold water line and then to the water heater in a closed loop.

Not An Improvement
 

So, when your friend wants to take a shower, he has to find his phone, use it to send a signal to start the pump and then wait for the 30 seconds or so for the "instant" tankless heater to send hot water to the shower. How is that better than just turning on the shower and waiting 30 seconds?

recirculation Pump with a Tank less Hotwater Heater
 

Ok, A thankless hot water heater takes water from the feed and, On Demand, heats it and it flows to the open valve, eg the shower, a sink etc. What, exactly do you think you are going to recirculate, and if you recirculate it where are you goinng to recirculate to? To a tank, then what? Are you going to heat it again?

The plumbers I spoke with said that this system, not brand, see post 16, is the only way to get instant hot water. I mentioned in my previous post that you can’t do it in the shower. So not instant but much quicker. By the way, not cheap. I would gladly have a tank style heater any day, but still have a recirculating pump. Had that at my last two homes in Ohio. JMO

No, most have either a google speaker or alexa speaker where you can set up a routine called "hot water" or whatever you prefer. The routine will turn on the water heater pump for "x" minutes, however long it takes depending on you home, then turn it off. So, when you need hot water for anything like a shower, just say "Hey Google, Hot Water" and by the time you get ready, your shower water will be hot since the circulator pump and by-pass device will have had enough time to push hot water through your pipes.

Works great, simple to set up and uses the least amount of water and energy to get hot water to your shower for example.

Here in the Villages, there might be some larger homes where other solutions might be needed but the Watts circulator and bypass valve solution works well and you don't have to spend a lot of money for a localized hot water heater. The trick is to connect it up to a wifi switch and then control it with your Google or Alexa speaker which many have. If not, for around $50, you can get one on Amazon and set it up.